A node in a wireless communication network mostly comprises at least one antenna arrangement. Such antenna arrangements are in many cases adapted for at least one of beam tilt in elevation, beam tilt in azimuth and adjustable beam width. However, for antennas with orthogonally dual polarized antenna elements, it is desirable that the orthogonality is maintained when the antenna beam or antenna beams are changed.
WO 2011/095184 discloses an antenna system with two ports arranged for dual polarized beam forming with interleaved elements in antenna arrays. It is shown how antenna elements with odd number in columns with odd number and antenna elements with even number in columns with even number are connected to one network, and how the remaining antenna elements, i.e. even antenna elements in odd columns and odd antenna elements in even columns with another network.
The feeding of interleaved antenna arrays leads to many problems such as grating lobes or high coupling between the antenna elements. Using lossless distribution networks will lead to reflection and coupling between ports connected to antenna side. Those reflections will in turn lead high to standing wave patterns and losses in the cables connecting different parts of the feeding networks at certain frequencies depending on the total path length in the networks. This easily deteriorates the achieved antenna patterns.
Also, since the feeding networks are disjoint, explicit care must be taken in adjusting the required phase shifters so that orthogonal patterns are achieved in every direction.
There is thus a need for a node in a wireless communication network which comprises at least one mobile communication dual polarized antenna where the orthogonality between its polarizations is maintained when the antenna beam or antenna beams are changed without the disadvantages of prior art arrangements.